Development and Validation of a Hybrid RANS-LES Approach Based on Temporal Filtering

To address the challenge of controlling the energy partition in hybrid RANS-LES methods, the use of a consistent operator based on temporal filtering is desirable. This formalism leads to the development of a consistent continuous hybrid RANS-LES approach called Hybrid Temporal LES (HTLES). In this paper, an upgraded version of HTLES is presented, focusing on improving the model for wall-bounded flows. Notably, a shielding function is integrated in the model to impose the RANS behavior in the near-wall regions. The calibration and validation of the hybrid method applied to the standard k-ω-SST model is then carried out on several test cases: decaying isotropic turbulence, channel flow and periodic-hill flow. The new version of the model fulfills the specifications: the correct subfilter dissipation; the correct migration from RANS to LES in the boundary layer; the robustness of the results to grid coarsening; the accuracy of the predictions at a reasonable computational cost.